Magnetoresistive stacks and methods therefor

Abstract

A magnetoresistive device may include a tunnel barrier region, a magnetically fixed region positioned on one side of the tunnel barrier region, and a magnetically free region positioned on an opposite side of the tunnel barrier region. The magnetically free region may include a plurality of ferromagnetic regions and at least one nonmagnetic insertion region. At least one ferromagnetic region of the plurality of ferromagnetic regions may include a multi-layer structure comprising a first layer of cobalt, and a second layer including at least one of platinum or palladium

What is claimed is: 
     
         1 . A magnetoresistive device, comprising:
 a tunnel barrier region;   a magnetically fixed region positioned on one side of the tunnel barrier region; and   a magnetically free region positioned on an opposite side of the tunnel barrier region, wherein the magnetically free region includes a plurality of ferromagnetic regions and at least one nonmagnetic insertion region, and wherein at least one ferromagnetic region of the plurality of ferromagnetic regions includes a multi-layer structure comprising:
 a first layer of cobalt; and 
 a second layer including at least one of platinum or palladium. 
   
     
     
         2 . The magnetoresistive device of  claim 1 , wherein the insertion region includes at least one of tantalum, tungsten, molybdenum, ruthenium, rhodium, rhenium, iridium, chromium, hafnium, zirconium, or osmium. 
     
     
         3 . The magnetoresistive device of  claim 1 , wherein each layer of the multi-layer structure includes a thickness between about 1-6 Å. 
     
     
         4 . The magnetoresistive device of  claim 1 , wherein at least one ferromagnetic region of the plurality of ferromagnetic regions includes an alloy of cobalt, iron, and boron. 
     
     
         5 . The magnetoresistive device of  claim 1 , wherein at least one ferromagnetic region of the plurality of ferromagnetic regions includes an alloy of cobalt, iron, and boron, and
 wherein the at least one ferromagnetic region includes an iron rich region at an interface of the at least one ferromagnetic region and the tunnel barrier region.   
     
     
         6 . The magnetoresistive device of  claim 1 , whereon at least one ferromagnetic region of the plurality of ferromagnetic regions includes adjacently positioned regions of a boron-free ferromagnetic layer and a boron-containing ferromagnetic layer. 
     
     
         7 . The magnetoresistive device of  claim 1 , wherein the tunnel barrier region is a first tunnel barrier region and the magnetically fixed region is a first magnetically fixed region, and wherein the magnetoresistive device further comprises:
 a second tunnel barrier region positioned on a side of the magnetically free region opposite the first tunnel barrier region; and   a second magnetically fixed region positioned on a side of the second tunnel barrier region opposite the magnetically free region.   
     
     
         8 . The magnetoresistive device of  claim 1 , wherein the multi-layer structure includes at least two layers of cobalt separated by a layer of platinum or palladium. 
     
     
         9 . The magnetoresistive device of  claim 1 , wherein the multi-layer structure includes at least five layers of cobalt. 
     
     
         10 . The magnetoresistive device of  claim 1 , wherein the tunnel barrier region includes one of magnesium oxide and aluminum oxide. 
     
     
         11 . A method of fabricating a magnetoresistive device, comprising:
 forming a magnetically fixed region;   forming a tunnel barrier region on one side of the magnetically fixed region;   forming a magnetically free region on an opposite side of the tunnel barrier region, wherein forming the magnetically free region includes forming a plurality of ferromagnetic regions separated by a nonmagnetic insertion region, and wherein forming at least one ferromagnetic region of the plurality of ferromagnetic regions includes forming a first layer of cobalt adjacent to a first layer of platinum or palladium.   
     
     
         12 . The method of  claim 11 , wherein the first layer of cobalt or the first layer of platinum or palladium includes a thickness between about 1-6 Å. 
     
     
         13 . The method of  claim 11 , wherein the insertion region includes at least one of tantalum, tungsten, molybdenum, ruthenium, rhodium, rhenium, iridium, chromium, or osmium. 
     
     
         14 . The method of  claim 11 , wherein forming the plurality of ferromagnetic regions includes forming at least one ferromagnetic region of the multiple ferromagnetic regions to include an alloy of cobalt, iron, and boron. 
     
     
         15 . The method of  claim 11 , wherein forming the plurality of ferromagnetic regions includes forming at least one ferromagnetic region of the plurality of ferromagnetic regions to include an alloy of cobalt, iron, and boron, and
 wherein forming the at least one ferromagnetic region includes forming an iron rich layer at an interface of the at least one ferromagnetic region and the tunnel barrier region.   
     
     
         16 . The method of  claim 11 , wherein the tunnel barrier region is a first tunnel barrier region and the magnetically fixed region is a first magnetically fixed region, and wherein the method further comprises:
 forming a second tunnel barrier region on a side of the magnetically free region opposite the first tunnel barrier region; and   forming a second magnetically fixed region on a side of the second tunnel barrier region opposite the magnetically free region.   
     
     
         17 . The method of  claim 11 , whereon forming the plurality of ferromagnetic regions includes forming at least one ferromagnetic region of the plurality of ferromagnetic regions by depositing adjacently positioned regions of a boron-free ferromagnetic layer and a boron-containing ferromagnetic layer. 
     
     
         18 . The method of  claim 11 , further comprises forming a second layer of cobalt adjacent to the first layer of platinum or palladium on a side opposite to the first layer of cobalt. 
     
     
         19 . The method of  claim 11 , further comprises forming a second layer of cobalt and a second layer of platinum or palladium. 
     
     
         20 . The method of  claim 11 , wherein forming the tunnel barrier region includes depositing an oxidizable material and oxidizing the deposited oxidizable material.